1. Field of the Invention
The present invention relates generally to the field of oxygenators used to increase the oxygen level in a patient's blood. More particularly, the present invention involves a percutaneous oxygenator that can be positioned within a patient's body, as for example in the inferior vena cava, superior vena cava, the right atrium of the heart, or any combination thereof.
2. Statement of the Problem
Many types of blood oxygenators are well known in the art. For example, during open heart surgery, the patient is interconnected with an external oxygenator, commonly known as a heart-lung machine, which introduces oxygen into the blood system. Most types of oxygenators use a gas-permeable membrane. Blood flows along one side of the membrane, and oxygen is supplied to the other side of the membrane. Given a sufficient pressure gradient between the oxygen supply and the blood, the oxygen will diffuse through the membrane and into the blood. In addition, carbon dioxide will tend to diffuse from the blood into the membrane.
In other situations, a smaller, implantable oxygenator may be sufficient to adequately supplement the patient's cardiopulmonary function by marginally increasing the oxygen content of the patient's blood. For example, patients suffering from emphysema, pneumonia, congestive heart failure, or other chronic lung disease often have blood oxygen partial pressures of approximately 40 torr. A relatively small increase of 10% to 20% is generally sufficient to adequately maintain the patient. This is a particularly desirable alternative in that it avoids the need to intubate the patient in such cases. In addition, temporary use of this type of oxygenator is sufficient in many cases to tide the patient over an acute respiratory insult. Placing such patients on a conventional respirator is often the beginning of a progressive downhill spiral by damaging the patient's pulmonary tree and thereby causing greater dependence on the respirator.
A number of devices and processes have been invented in the past incorporating this basic technology, including the following:
______________________________________ Inventor Patent No. Issue Date ______________________________________ Bodell 3,505,686 Apr. 14, 1970 Burton 4,159,720 July 3, 1979 Kopp, et al. 4,346,006 Aug. 24, 1982 Mortensen 4,583,969 Apr. 22, 1986 Taheri 4,631,053 Dec. 23, 1986 Kitagawa, et al. 4,743,250 May 10, 1988 ______________________________________
The Bodell patent demonstrates the general concept of using gas permeable fibers to boost the oxygen level of blood. FIGS. 6 and 10 show two variations of this device intended for use inside the body of the patient. In the implantable embodiment of the Bodell device, a tubular casing serves as a shunt either from the pulmonary artery to the left atrium of the heart (FIG. 6), or more generally between an artery and a vein (FIG. 10). A multitude of parallel-connected capillary tubes are used to oxygenate and/or purify the blood circulating through the casing.
FIGS. 3-5 of the Mortensen patent show a transvenous oxygenator made of a plurality of small diameter gas permeable tubes 32 connected to headers 34 and 36 at each end. However, the specific device disclosed by Mortensen has a significant disadvantage in that two incisions are required. The insertion process is also rather complex.
The Taheri patent discloses a transvenous oxygenator having a single membrane 16 through which oxygen diffuses. The membrane is disposed within a sheath 18 and both are supported by a flexible wire 20.
The remaining references are of lesser pertinence.
3. Solution to the Problem
None of the prior art references uncovered in the search show oxygenation by means of a number of parallel loops of hollow tubes supported by a wire stylet that is inserted through a single small incision. Furthermore the unique Y-shaped connector used in the present invention is also not disclosed in any of these references.